[NewPM][opt] Revert to legacy PM when any codegen passes are specified

This reduces the number of check-llvm failures by 500.

Ideally we'd have a codegen version of PassRegistry.def, or have all the
codegen passes ported and put into PassRegistry.def. But since that
doesn't exist yet, hardcode the list of codegen IR passes.

There are still codegen passes missing from this list, I'll add them
later as I stumble upon them.

Reviewed By: asbirlea, ychen

Differential Revision: https://reviews.llvm.org/D84872

llvm/tools/opt/opt.cpp

@@ -486,6 +486,41 @@ struct TimeTracerRAII {
   }
 };
 
+// For use in NPM transition.
+// TODO: use a codegen version of PassRegistry.def/PassBuilder::is*Pass() once
+// it exists.
+static bool IsCodegenPass(StringRef Pass) {
+  std::vector<StringRef> PassNamePrefix = {
+      "x86-",    "xcore-", "wasm-",  "systemz-", "ppc-",    "nvvm-",
+      "nvptx-",  "mips-",  "lanai-", "hexagon-", "bpf-",    "avr-",
+      "thumb2-", "arm-",   "si-",    "gcn-",     "amdgpu-", "aarch64-"};
+  std::vector<StringRef> PassNameContain = {"ehprepare"};
+  std::vector<StringRef> PassNameExact = {
+      "safe-stack",           "cost-model",
+      "codegenprepare",       "interleaved-load-combine",
+      "unreachableblockelim", "sclaraized-masked-mem-intrin"};
+  for (const auto &P : PassNamePrefix)
+    if (Pass.startswith(P))
+      return true;
+  for (const auto &P : PassNameContain)
+    if (Pass.contains(P))
+      return true;
+  for (const auto &P : PassNamePrefix)
+    if (Pass == P)
+      return true;
+  return false;
+}
+
+// For use in NPM transition.
+static bool CodegenPassSpecifiedInPassList() {
+  for (const auto &P : PassList) {
+    StringRef Arg = P->getPassArgument();
+    if (IsCodegenPass(Arg))
+      return true;
+  }
+  return false;
+}
+
 //===----------------------------------------------------------------------===//
 // main for opt
 //
@@ -685,7 +720,12 @@ int main(int argc, char **argv) {
   if (OutputThinLTOBC)
     M->addModuleFlag(Module::Error, "EnableSplitLTOUnit", SplitLTOUnit);
 
-  if (EnableNewPassManager || PassPipeline.getNumOccurrences() > 0) {
+  // If `-passes=` is specified, use NPM.
+  // If `-enable-new-pm` is specified and there are no codegen passes, use NPM.
+  // e.g. `-enable-new-pm -sroa` will use NPM.
+  // but `-enable-new-pm -codegenprepare` will still revert to legacy PM.
+  if ((EnableNewPassManager && !CodegenPassSpecifiedInPassList()) ||
+      PassPipeline.getNumOccurrences() > 0) {
     if (PassPipeline.getNumOccurrences() > 0 && PassList.size() > 0) {
       errs()
           << "Cannot specify passes via both -foo-pass and --passes=foo-pass";